Ligation is a procedure in which a thread, wire or band are applied around a tissue structure or area to constrict it thereby preventing flow of blood or other body fluids. Band ligation involves applying a highly elastic band around a tissue site to constrict it. Ligation may be used to treat varices, polyps, hemorrhoids, or other lesions. After application of a ligator at the treatment site, bleeding is stopped and the tissue below the ligature then begins to heal and fuse together while the tissue above the ligature becomes necrotic and eventually separates from the site. Band ligators are devices that are used to deliver an elastic band in an expanded configuration to a tissue location then release it around the treatment site permitting it to return to its relaxed orientation to constrict the tissue. Band ligators have been adapted to be attached to the distal end of endoscopes to facilitate application of bands to treatment sites in natural body lumens such as the esophagus or rectum. Endoscopic band ligators have become especially useful in treating esophageal varices. A band ligator attached to the distal end of a flexible viewing endoscope can be navigated, visually, directly to a varix location to accurately apply a ligating band.
Multiple band endoscopic ligators are shown in U.S. Pat. Nos. 6,042,591, 6,136,009 and 6,436,108, all of which are incorporated by reference herein. Those multiple band ligators operate to dispense ligating bands by arranging a plurality of bands along an inner cylinder that is mounted over the distal end of an endoscope and reciprocally operating an outer cylinder, slidable over the inner cylinder to push off bands individually from the inner cylinder. Projecting fingers extending radially inward from the outer cylinder engage the bands individually so that they may be pushed off one at a time onto the aspirated varix. In moving the outer cylinder longitudinally relative to the inner cylinder and several bands, a performance concern is being able to reliably position the inwardly projecting fingers behind a single ligating band and reliably discharging that single band to the varix. Because of inherent inaccuracies in the remote operation of the outer cylinder, more than one band could be inadvertently released at a single site or the device could fail to release any bands at the location. Further frustrating this problem is the fact that the physician may not realize that a single band is not successfully released at the desired location. It is an object of the present invention to improve the reliability with which a single band can be released from the ligating device at a treatment site.
Another concern with the accurate operation of a multiple band endoscopic ligating device centers on the physician's ability to remotely control the device from outside the patient. Control handles for operating ligating devices have been somewhat primitive and may require two hands to operate. Two handed operation of the ligator control handle is especially problematic in the endoscopic context because at least one hand must be used to operate endoscope controls for articulating the distal end of the endoscope so that it may be properly navigated. As a result, operation of know endoscopic band ligators typically requires two people to operate all the necessary controls at the proximal end of the endoscope. It is an object of the present invention to provide an endoscopic band ligator control handle that can be operated with a single hand while maintaining control of the endoscope shaft.
Another concern with the remote operation of the band ligating device is the accuracy with which the band dispenser component can be operated to insure release of a single band. Cable operated band dispensers lose tactile feel and accurate movement due to the flexibility inherent in the cable and in the unstable sliding movement of the small ligator components that move to release the bands. More accurate operation of the band ligator controls would enhance the reliability of the band release from the device. It is an object of the invention to improve the remote operation of the band ligator components for accurate band release.